Manufacture of electron-discharge devices



July 14; '1925. 1,545,591

J. J. MADINE MANUFACTURE OF ELECTRON DISCHARGE DEVICES Filed March 6, 1923 Patented July 14, 1925,

UNITED STATES FICE.

JOHN J. MADINE, OF NEWARK, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, 015 NEW YORK, N. Y., A CORPORATION OF NEW YORK.

MANUFACTURE OF ELECTRON-DISCHARGE DEVICES.

Application filed March 6, 1923. Serial No. 623,188.

To all whom it may concern:

Be it known that I, JOHN 'J. MADINE, a citizen of'the United States, residing at Newark, in the county of Essex, State of New Jersey, have invented certain new and useful Improvements in the Manufacture of Electron-Discharge Devices, of which the following is. a full, clear, concise, and exact description.

This invention relates to the manufacture of electron discharge devices such as vacuum tubes and has for its object a tight seal between the leading-in wires and the glass envelope.

ordinarily composed of lead glass to which is fused. a stem composed of the more expensive potash glass. The reason for uslng potash glass in the stem lies in the fact' that platinum seals much better in potash glass than it does in lead glass. Lead glass is used to reduce the cost of the device as is less expensive than potash glass but equally good as an envelope.

In electron discharge devices having large potential differences impresesd between the grid and anode it is not practical to seal all the leading-in wires end of the stem because for the anode and grid cannot be placed sufliciently far apart to obtain the necessary insulation. It is therefore common practice in tubes of this leading-in wires for the anode and id at the juncture of the stem flare and t e enthe leading-1n Wires velopeat points opposite each other so' that the necessary insulation is obtained.

This invention insures a tight seal for these leading-in wires by providing on the platinum portion of the leading-in wire a bead of potash glass which is fused to the glass of the containing vessel, the bead beingthe-finished seal.

In Fig. 1, 10 is a lead glass envelope and The enclosing vessel of an electron dis-: charge device consists of a tube or envelope in the press at the.

character to seal in the,

sealing in the grid and anode leading-in wires, and Fig. 3 discloses 11 is the stem from which is supported the electrode assembly 12. The leading-inwires 13 for the cathodearc sealed inthe press at the end of the stem. The leading-in wire 1% for the grid electrode comprises a coil of wire from the lower end ofwhich is suspended a short piece of platinum wire 15.

The leading-in wire 16 for the anode likewise comprirjes a coil of wire and a piece of platinum wire 17.

The'sealing of the stem to the envelope and the sealing in of the platinum wires 15 and 17 is accomplished in the following 16. Short glass tubes-19 are fused to theglass vessel in alignment with the apertures.

A tool is now thrust through each tube 19 and its -corresponding aperture, and the end of a leading wire gripped and pulled out so that the platinum portion lies outside the vessel. A bead 20 of potash glass is applied to the platinum portion and is then fused to the end of a tube 19 to' close it,

resulting in the arrangement shown in Fig. 3.

This'insures a tight seal for the leadingin Wires as'the bead of potash glass seals tightly tothe platinum portion of the leading-in wires and then fuses to the tube 19 to form a gas-tight vessel. V The use of the glass tubes 19 reduces thenumber of devices defective because of cracked seals. For, any crack developing around the seal during subsequent heating in evacuating the device is lim1ted to the tubes and does notextend to the vessel itself. It is, therefore, possibleto merely soften the glass of the tubes 19 and bv sli ht manipulation close such a crack with littlev effort, whereas if the crack had extended to the vessel itself much working would not be possible.

What is claimed is:

1. The method of manufacturing electron discharge devices which comprises fusing together an envelope and stem of different llO types of glass, forming an aperture at the juncture of said different types, arranging a leading-in Wire in said aperture, applying a bead of glass to said leading-in Wire, and

fusing said bead to the remaining glass to the leading-in wires completely within the vessel, forming holes in the vessel, drawing said leading-in wires through said holes, applying glass beads to said leading-in Wires, and closing said holes with said heads.

'3. In an electron discharge device, a vessel comprising an envelope of one type of glass, a stem of another type of glass, electrodes supported by said stem, leading-in wires for said electrodes passing through said vessel at the juncture of said envelope and said stem, and a head of the same kind of glass as the stem surrounding said leading-in wire and fused to said containing vessel.

4. The method of manufacturing electron discharge devices which comprises forming an aperture in the enclosing vessel thereof, drawing a leading-in Wire through said aperture, applying a bead of glass to said leading-in wire, and sealing said glass bead to said envelope to close said aperture.

5. The method of manufacturing electron discharge devices which comprises fusing together an envelope of lead glass and a stem of potash glass to form an enclosing vessel, forming an aperture at the juncture of said potash and lead glass, applying a bead of potash glass to a leadingdn wire, and fusing said bead to the enclosing vessel to close said aperture.

6. In an electron discharge device, an enenvelope and stem, a glass tube sealed to.

said vessel and enclosing said leading wire, and a glass bead fused to said leading-in wire and to the end of said tube.

8. The method of manufacturing electron discharge devices which comprises fusing together an envelope and a stem of difter'ent kinds of glass to form a containing vessel, forming an aperture at the juncture of said stem and envelope, fusing a glass tube to said vessel in alignment with said aperture, fusing a bead of glass to a leading-in wire, and closing said tube with said bead.

In witness whereof, I hereunto subscribe my name this 1st day of March A. D., 1923.

JOHN J. MADINE. 

